System and method for accessing a cartridge cell that compensates for misalignment between the system and the cell

ABSTRACT

According to an embodiment, a method for accessing a cell includes: a first access step of taking out a cartridge from the cell or inserting the cartridge into the cell in an initial stop position; and a second access step of taking out the cartridge from the cell or inserting the cartridge into the cell in one or more positions in the vicinity of the initial stop position until the taking-out or insertion operation succeeds in a case where the first access step has failed.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a system and method for accessing acell that take out/insert a cartridge from or into the cell, and moreparticularly, to a system and method for accessing a cell that move apicker mechanism, which is used for carrying the cartridge, to the frontof a target cell among a plurality of cells arranged in a matrix form ina magazine, and then, take out a cartridge that has been inserted intothe target cell and put the cartridge on the picker mechanism, or unloada cartridge that has been put on the picker mechanism and insert thecartridge into the target cell.

2. Description of the Related Art

Programs and data used in a computer are, in general, stored in a harddisk drive and transferred, as needed, from the hard disk drive to amain memory at execution time of the program. The hard disk drive isconstantly at the risk of being damaged, and a given limitation isimposed on the capacity thereof. Therefore, a backup device that canstore a large volume of programs and data with high reliability isrequired, even if the backup device operates at a low speed. As thebackup device, a magneto-optical disk drive, a DVD drive, a tape drive,and the like are available. Among them, a magnetic tape drive isexcellent in terms of reliability, storage capacity, andcost-performance, and a collective magnetic tape drive is used in orderto back up a tremendous volume of data.

A magazine is mounted on the collective magnetic tape drive. Themagazine is proved with a plurality of cells arranged in a matrix form.Each cell houses a magnetic tape cartridge (hereinafter, referred tomerely as “cartridge”). An accessor mechanism including a pickermechanism takes out a cartridge required in each occasion from a cellthat houses the cartridge and feeds the taken out cartridge to a tapedrive. After completion of recording or reproduction operation in thetape drive, the accessor mechanism feeds the cartridge from the tapedrive to the cell and inserts the cartridge into the cell.

It is necessary that the picker mechanism that carries a cartridge iscorrectly stopped at the front of the target cell in order to completethe taking-out/insertion operation of the cartridge from/into the targetcell normally. The size of the conventional collective magnetic tapedrive was comparatively large, and accordingly a distance between theadjacent cells was comparatively long, so that accuracy of the stopposition of the picker mechanism has not been strictly required.

However, a high-capacity collective magnetic tape drive with a smallsize has been recently required. In order to obtain such a small-sizedcollective magnetic tape drive, the size of the magazine, which is agreat factor that determines the size of the collective magnetic tapedrive, must be reduced under the condition that the number of cartridgesthat can be housed in the collective magnetic tape drive should be equalor more than the number of cartridges in the conventional collectivemagnetic tape drive. Therefore, assuming that the same cartridges asused in the conventional tape drive are used, a distance between theadjacent cells must be reduced as much as possible. This accordinglyrequires an increase in the accuracy of the stop position of the pickermechanism relative to the cell. Even if a position control servo is usedto improve the accuracy of an absolute stop position of the pickermechanism at shipment time, it is difficult to improve or maintain theaccuracy of the stop position of the picker mechanism relative to thecell due to attachment errors, dimension errors, distortion, wear ofmovable parts, secular change and the like of mechanical partsconstituting the magazine.

SUMMARY OF THE INVENTION

An object of the present invention is therefore to provide a system andmethod for accessing a cell capable of completing thetaking-out/insertion of a cartridge from/into a cell even in a casewhere the stop position of the picker mechanism is misaligned relativeto the target cell.

Another object of the present invention is to provide a system andmethod for accessing a cell capable of compensating the misalignment ofthe stop position of the picker mechanism relative to the target cell.

According to an aspect of the present invention, there is provided asystem for accessing a cell including: a first access means for takingout a cartridge from the cell or inserting the cartridge into the cellat an initial stop position; and a

second access means for taking out the cartridge from the cell orinserting the cartridge into the cell at one or more positions in thevicinity of the initial stop position until the taking-out or insertionoperation succeeds at the latest in a case where the first access meanshas failed to complete the taking-out or insertion operation.

The above system for accessing a cell may further include an initialstop position update means for updating the initial stop position in acase where the second access means has succeeded in the taking-out orinsertion operation in any of the positions in the vicinity of theinitial stop position, the update means updating the initial stopposition based on the position at which the access has succeeded.

The above system may further include an access cancel means forcanceling the taking-out or insertion operation of the second accessmeans in a case where the second access means has failed to complete thetaking-out or insertion operation at a predetermined number of positionsin the vicinity of the initial stop position.

In the above system, the one or more positions in the vicinity of theinitial stop position may include four positions apart from the initialstop position in the left, right, up and down directions.

In the above system, the one or more positions in the vicinity of theinitial stop position may include eight positions obtained by excludingthe initial stop position from nine positions arranged in a latticemanner at which four cross-shapes intersect with each other, the centersof the four cross lines extending from each of four positions apart fromthe initial stop position in the left, right, up and down directions.

In the above system, at least any one of the one or more positions inthe vicinity of the initial stop position may be set at the positionapart from the initial stop position in a particular direction by adistance not more than the length of a normal taking-out area or normalinsertion area.

In the above system, at least any one of the one or more positions inthe vicinity of the initial stop position may be set at the positionapart from the initial stop position in a particularly direction by adistance equal to the length of a normal taking-out area or normalinsertion area.

In the above system, at least any one of the one or more positions inthe vicinity of the initial stop position may be set at the positionapart from the initial stop position in a particular direction by adistance equal to the half of the length of a normal taking-out area ornormal insertion area.

In the above system, a difference between an initial stop positionbefore update and updated initial stop position in a particulardirection may be set to not more than the length of a normal taking-outarea or normal insertion area in the particular direction.

In the above system, a difference between an initial stop positionbefore update and updated initial stop position in a particulardirection may be set to equal to the length of a normal taking-out areaor normal insertion area in the particular direction.

In the above system, a difference between an initial stop positionbefore update and updated initial stop position in a particulardirection may be set to the half of the length of a normal taking-outarea or normal insertion area in the particular direction.

According to the invention, even if an initial stop position hasdeviated from the position for the first access means to succeed intaking-out or inserting operation of a cartridge from or into a cell,the second access means can complete the taking-out or insertingoperation of a cartridge from or into a cell. Therefore, even in a casewhere a predetermined mechanical accuracy cannot be obtained, thetaking-out or insertion of a cartridge from or into a cell can succeed.

According to the present invention, it becomes more likely that thefirst access means succeeds in the taking-out or insertion of acartridge from or into a cell in the next operation. This increases apossibility that eliminates a need for the second access means toperform the taking-out or insertion of a cartridge from or into a cellto reduce the time required for the taking-out or insertion of acartridge from or into a cell and electric power. Further, the life ofthe device can be prolonged. In a case where misalignment exists and isleft unattended, the misalignment increases, with the result that, inthe next operation time, not only the first access means but also thesecond access means may fail to complete the taking-out or insertion ofa cartridge from or into a cell. The present invention can eliminatesuch a possibility.

According to the present invention, unnecessary operation can beomitted.

According to the present invention, a possibility that the second accessmeans succeeds in the taking-out or insertion of a cartridge from orinto a cell can be increased under an X- and Y-axis position control.

According to the present invention, a possibility that the second accessmeans succeeds in the taking-out or insertion of a cartridge from orinto a cell can be increased under the X- and Y-axis position controleven in a case where an initial stop position has been misaligned bothin X- and Y-directions.

According to the present invention, a possibility that excesscompensation causes the second access means to fail to complete thetaking-out or insertion of a cartridge from or into a cell at thedirection opposite to the misalignment direction of the initial stopposition can be eliminated.

According to the present invention, taking-out feasible area orinsertion feasible area can be increased at a maximum.

According to the present invention, the second access means can performthe taking-out or insertion of a cartridge from or into a cell at theposition in the vicinity of the center of the normal taking-out area ornormal insertion area in a case where an initial stop position hasslightly deviated from the normal taking-out area or normal insertionarea.

According to the present invention, it is possible to prevent huntingand diverging phenomena from occurring at an initial stop position dueto update of the initial stop position.

According to the present invention, it becomes more likely that thefirst access means succeeds in the taking-out or insertion of acartridge from or into a cell in the next operation.

According to the present invention, an updated initial stop position canbe set at the position in the vicinity of the center of the normaltaking-out area or normal insertion area in a case where the initialstop position has slightly deviated from the normal taking-out area ornormal insertion area.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view showing a structure of a collectivemagnetic tape drive according to an embodiment of the present invention;

FIG. 2 is a perspective view showing a cartridge according to theembodiment of the present invention;

FIG. 3 is a front view showing a structure of a picker mechanismaccording to the embodiment of the present invention;

FIGS. 4A to 4D are views for explaining a taking-out operation of thecartridge from a cell according to the embodiment of the presentinvention;

FIGS. 5A to 5E are views for explaining an insertion operation of thecartridge into a cell according to the embodiment of the presentinvention;

FIG. 6 is a first flowchart for explaining an operation for accessing acell and an operation associated with the cell-access operationaccording to the embodiment of the present invention;

FIG. 7 is a second flowchart for explaining the operation for accessinga cell and the operation associated with the cell-access operationaccording to the embodiment of the present invention;

FIG. 8 is a third flowchart for explaining the operation for accessing acell and the operation associated with the cell-access operationaccording to the embodiment of the present invention;

FIGS. 9A to 9C are front view, side view, and back view, respectively,showing a detailed structure of the magazine according to the embodimentof the present invention;

FIG. 10 is a view showing a normal taking-out area according to theembodiment of the present invention;

FIG. 11 is a block diagram showing a device that performs the operationfor accessing a cell and the operation associated to the cell-accessoperation according to the embodiment of the present invention;

FIG. 12 is a view showing a normal taking-out area and a taking-outfeasible area according to the embodiment of the present invention; and

FIGS. 13A and 13B are views showing points to be accessed according tothe embodiment of the present invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

A preferred embodiment of the present invention will be described belowin detail with reference to the accompanying drawings.

FIG. 1 is a perspective view showing a structure of a collectivemagnetic tape drive according to the embodiment of the presentinvention. The collective magnetic tape drive includes a tape drive 101,two magazines 102 and an accessor mechanism 103. Each of the magazines102 includes a plurality of cells 105 arranged two dimensionally in X-and Y-directions. A cartridge 106 is housed in each of the cells 105.The accessor mechanism 103 includes a picker mechanism 104. The mainbody of the accessor mechanism 103 is movable in X-direction. The pickermechanism 104 is movable in Y-direction and can be rotated about Y-axis.

In order to complete loading of the cartridge 106 that has been insertedinto a certain cell into the tape drive 101, the following operation isperformed. That is, the position of the accessor mechanism 103 inX-direction is firstly shifted to the stop position corresponding to theposition of the target cell in X-direction, the position of the pickermechanism 104 in Y-direction is then shifted to the stop positioncorresponding to the position of the target cell in Y-direction, thepicker mechanism 104 is rotated to face the magazine 102 including thetarget cell, whereby the picker mechanism 104 faces the front of thetarget cell. After that, as described later, the cartridge 106 is takenout of the target cell and loaded into the picker mechanism 104. Then,the accessor mechanism 103 is shifted in X-direction, and the pickermechanism 104 is shifted in Y-direction and rotated to face the tapedrive 101. The cartridge 106 is then unloaded from the picker mechanism104 and loaded into the tape drive 101.

When the cartridge 106 that has been loaded into the tape drive 101 isset back to the cell, the operation opposite to the above is performed.

Referring to FIG. 2, notches 111 are formed at both side surfaces of thecartridge 106. Referring to FIG. 3, the picker mechanism 104 includes apicker arm 112. The picker arm 112 has an L-shape and is provided with anail 113. The picker arm 112 is movable in the depth direction of thepicker mechanism 104 as denoted by a two-headed arrow in FIG. 3.

An operation for taking out the cartridge 106 that has been insertedinto the cell 105 from the cell 105 and loading the cartridge into thepicker mechanism 104 will next be described below.

Firstly, as shown in FIG. 4A, the picker mechanism 104 is shifted to thefront of a desirable cell 105. In this state, the picker arm 112 hasbeen housed in the home position within the picker mechanism 104. Then,as shown in FIG. 4B, the picker arm 112 is forwarded in the depthdirection of the picker mechanism 104 to the side of the notch 111. Theaccessor mechanism 103 is then set back in X-direction as shown in FIG.4C to allow the nail 113 to engage with the notch 111. Next, as shown inFIG. 4D, the picker arm 112 is set back in the depth direction to thehome position thereof, whereby the cartridge 106 is taken out of thecell 105 and loaded into the picker mechanism 104.

An operation for unloading the cartridge 106 that has been loaded intothe picker mechanism 104 from the picker mechanism 104 and inserting thecartridge 106 into the cell 105 will next be described below.

Firstly, as shown in FIG. 5A, the picker mechanism 104 is shifted to thefront of a desired cell 105. In this state, the picker arm 112 has beenhoused in the home position within the picker mechanism 104, thecartridge 106 has been loaded into the picker mechanism 104, and thenail 113 has engaged with the notch 111. Then, as shown in FIG. 5B, thepicker arm 112 is forwarded in the depth direction of the pickermechanism 104 until the cartridge 106 has butted against the backboardof the cell 105. Next, as shown in FIG. 5C, the picker arm 112 isslightly set back in the depth direction to eliminate the contactbetween the nail 113 and notch 111. The accessor mechanism 103 is thenforwarded in X-direction as shown in FIG. 5D to release the engagementbetween the nail 113 and notch 111. Then, the picker arm 112 is set backto the home position thereof, as shown in FIG. 5E.

Referring to FIGS. 9A, 9B and 9C, a vertical partition board 120 forpartitioning the cells 105 adjacently arranged to each other inX-direction within the magazine 102 has a cavity portion 121 to avoidinterference with the picker arm 112 to be forwarded in the depthdirection. This can be seen from the perspective view of FIG. 1.Accordingly, in the cavity portion 121, the cells 105 that areadjacently arranged to each other in the horizontal direction directlyface each other without the vertical partition board 120 beinginterposed between the cells. The picker arm 112 enters the cavityportion 121. Further, a taper portion 123 is formed at the entrance ofthe vertical partition board 120. Likewise, a horizontal partition board(not shown) for partitioning the cells 105 adjacently arranged to eachother in Y-direction has a taper portion. Accordingly, the taperportions are formed in four sides of the cell 105 at the entrance of thecell. By forming the taper portions as described above, even when thestop position of the picker mechanism 104 is misaligned with the frontof the target cell 105, it is possible to absorb the misalignment tocomplete insertion of the cartridge 106 into the target cell 105.Further, a shroud that surrounds the cartridge 106 that has been loadedinto the picker mechanism 104 has taper portions, by which even when thestop position of the picker mechanism 104 is misaligned with the frontof the target cell 105, it is possible to absorb the misalignment tocomplete loading of the cartridge 106 into the picker mechanism.

A plate spring is formed on the right surface of the vertical partitionboard 120, which pushes the cartridge 106 that has been inserted intothe cell 105 in the right direction (direction in which X-coordinateincreases). Therefore, as shown in FIG. 9A, a cavity portion 122 isformed between the vertical partition board 120 and cartridge 106.

Next, a description will be given of a case where an access fails. Theterm “access” mentioned here denotes the taking-out of the cartridge 106from the cell 105, which has been described with reference to FIGS.4A-4D, or the insertion of the cartridge 106 into the cell 105, whichhas been described with reference to FIGS. 5A-5E. The coordinate of thecell 105 to be accessed has been determined in the device design, andthe accessor mechanism 103 and picker mechanism 104 are shifted to thestop position corresponding to the coordinate by the position servocontrol. However, the picker mechanism 104 is not always stopped at thefront of the cell 105 due to attachment errors, dimension errors, ordistortion of the magazine 102 and the like. When the misalignment ofthe stop position of the picker mechanism 104 has exceeded the allowablevalue, the access will fail.

Firstly, the allowance value of the misalignment of the stop position atthe taking-out time will be described. The allowance value will notexceed the taper amount of each of the taper portions of the shroud inthe picker mechanism 104 with respect to plus X-direction, minusX-direction, plus Y-direction, and minus Y-direction. Therefore, theproblem lies in whether the factor other than the taper amount furtherreduces the allowable value. Note that when the misalignment hasexceeded the taper amount, the cartridge 106 butts against the shroud inthe process when the picker arm 112 is set back in the depth direction,so that the taking-out of the cartridge fails.

When the leading edge of the picker arm 112 butts against the frontsurface of the cartridge 106 in the process when the picker arm 112 isforwarded in the depth direction, the taking-out of the cartridge fails.This occurs in a case where the misalignment is larger than the taperamount in the design dimension, and does not become a restriction on theallowable value. Note that at the time point when the leading edge ofthe picker arm 112 butts against the front surface of the cartridge 106,an error occurs to cause the taking-out operation to fail.

When the accessor mechanism 103 is set back in X-direction to allow thenail 113 to engage with the notch 111, the cavity portion 122 ismaintained, and a cavity portion 124 (see FIG. 9) between the bottomsurface of the notch 111 and leading edge of the nail 113 is alsomaintained in normal cases. However, when the stop point of the accessormechanism 103 is excessively misaligned in minus X-direction, the bothcavity portions 122 and 124 are eliminated. In this case, an erroroccurs while the accessor mechanism 103 is set back in X-direction tocause the taking-out operation to fail. This can be a restriction on theallowable value because the sum of the dimensions of the cavity portions122 and 124 are smaller than the taper amount.

When the stop position of the accessor mechanism 103 is excessivelymisaligned in plus X-direction, the nail 113 cannot engage with thenotch 111 even if the accessor mechanism 103 is set back in X-direction.However, in the design dimension, the misalignment in a case where theengagement cannot be made is larger than the taper amount. Therefore,this does not become a restriction on the allowable value. Note that, inthe case described above, the cartridge 106 is not loaded into thepicker mechanism 104 even after the completion of a series of thetaking-out operations, so that the cartridge 106 cannot be taken out.

When the stop position of the picker mechanism 104 is excessivelymisaligned in minus Y-direction, the leading edge of the picker arm 112butts against the horizontal partition board in the process when thepicker arm 112 is forwarded in the depth direction to cause thetaking-out operation to fail. However, in the design dimension, themisalignment in a case where the butting occurs is larger than the taperamount. Therefore, this does not become a restriction on the allowablevalue.

When the stop position of the picker mechanism 104 is excessivelymisaligned in plus Y-direction, the leading edge of the nail 113 doesnot engage with the notch 111 but butts against the side surface of thecartridge 106 in the process when the accessor mechanism 103 is set backin X-direction to cause the taking-out operation to fail. However, inthe design dimension, the misalignment in the case described above islarger than the taper amount. Therefore, this does not become arestriction on the allowable value.

As described above, the allowable value in the taking-out time isdetermined as shown in FIG. 10 with respect to plus X-direction, minusX-direction, plus Y-direction, and minus Y-direction, although allrestriction factors are not explained. In order for the taking-outoperation to be normally completed, the stop position of the pickermechanism 104 must fall within the square (normal taking-out area) 131denoted by oblique lines in FIG. 10.

Also as to the insertion operation, the area (normal insertion area)same as the normal taking-out area 131 shown in FIG. 10, where theinsertion operation is normally completed is determined depending on thetaper amount and other restriction factors. Note that the normalinsertion area 131 is not always the same as the normal taking-out area.

When the stop position of the picker mechanism 104 does not fall withinthe normal taking-out area, an error occurs in any of the processes inthe taking-out operation to cause the taking-out operation to fail.Likewise, when the stop position of the picker mechanism 104 does notfall within the normal insertion area, an error occurs in any of theprocesses in the insertion operation to cause the insertion operation tofail.

In the present embodiment, an operation for accessing a cell and anoperation associated with the cell-access operation as described beloware performed using a ROM 301, a CPU 302, a rewritable nonvolatilememory 303, an input/output interface (I/O) 304, a servo section 305 andan error detection section 306 shown in FIG. 11. This access operationincludes a stop position compensation function. The term “stop position”mentioned here is the stop position of the accessor mechanism 103 inX-direction and the stop position of the picker mechanism 104 inY-direction, which determines the stop positions of the picker mechanism104 and picker arm 112 relative to a target cell, and determines thestop position of the cartridge 106 relative to a target cell in the caseof the insertion operation of the cartridge 106 into the cell 105, whichhas been described with reference to FIG. 5. Although the rotation ofthe picker mechanism 104 is not mentioned in the following description,the picker mechanism 104 actually is rotated to face the magazine 102including a target cell in the access time and is rotated to face thetape drive 101 at the loading time. The CPU 302 reads in and executes aprogram stored in the ROM 301 to perform each part in the followingoperations. The rewritable nonvolatile memory 303 stores the stoppositions in X- and Y-directions corresponding to each cell. The servosection 305 shifts the accessor mechanism 103 to the stop positionthereof in X-direction and an area in the vicinity of the stop positionand shifts the picker mechanism 104 to the stop position thereof inY-direction and an area in the vicinity of the stop position. The errordetection section 306 detects that the access has not been normallycompleted. The I/O 304 interfaces between the CPU 302 and servo section305 and between the CPU 302 and error detection section 306.

Referring to FIG. 6, the stop positions in X-direction X(i, j) andY-direction Y(i, j) corresponding to a target cell (cell(i, j), where iis an integer from 1 to m, and j is an integer from 1 to n) are firstlyread out from the rewritable nonvolatile memory 303. The read out stoppositions in X-direction X(i, j) and Y-direction Y(i, j) are set as aninitial stop position (step S201). The accessor mechanism 103 is thenshifted to the stop position in X-direction X(i, j) (step S202), and thepicker mechanism 104 is shifted to the stop position in Y-direction Y(i,j) (step S203). With the above operation, the picker mechanism 104reaches the initial stop position. Next, the access operation is carriedout (step S204). After that, it is determined whether the accessoperation of step S204 has been normally completed (step S205). When ithas been determined that the access operation of step S204 has beennormally completed (Yes in step S205), the flow advances to step S229(FIG. 8).

When it has been determined that the access operation of step S204 hasnot been normally completed (No in step S205), the accessor mechanism103 is shifted to X(i, j)+αx (step S207). The stop position of thepicker mechanism 104 in Y-direction is maintained at Y(i, j). Next, theaccess operation is carried out (step S208). After that, it isdetermined whether the access operation of step S208 has been normallycompleted (step S209). When it has been determined that the accessoperation of step S208 has been normally completed (Yes in step S209),αx/βx is added to X(i, j)(step S210), the obtained X(i, j) is writteninto the rewritable nonvolatile memory 303 (step S211), and the flowadvances to step 229 (FIG. 8).

When it has been determined that the access operation of step S208 hasnot been normally completed (No in step S209), the accessor mechanism103 is shifted to X(i, j)−αx (step S212). The stop position of thepicker mechanism 104 in Y-direction is maintained at Y(i, j). Next, theaccess operation is carried out (step S213). Then, it is determinedwhether the access operation of step S213 has been normally completed(step S214), as shown in FIG. 7. When it has been determined that theaccess operation of step S213 has been normally completed (Yes in stepS214), αx/βx is subtracted from X(i, j) (step S215), the obtained X(i,j) is written into the rewritable nonvolatile memory 303 (step S216),and the flow advances to step S229 (FIG. 8).

When it has been determined that the access operation of step S213 hasnot been normally completed (No in step S214), the accessor mechanism103 is shifted to X(i, j)(step S217), and the picker mechanism 104 isshifted to Y(i, j)+αY (step S218). Next, the access operation is carriedout (step S219). After that, it is determined whether the accessoperation of step S219 has been normally completed (step S220). When ithas been determined that the access operation of step S219 has beennormally completed (Yes in step S220), αY/βY is added to Y(i, j)(stepS221), the obtained Y(i, j) is written into the rewritable nonvolatilememory 303 (step S222), and the flow advances to step S229 (FIG. 8).

When it has been determined that the access operation of step S219 hasnot been normally completed (No in step S220), the picker mechanism 104is shifted to Y(i, j)−αY (step S223). The stop position of the accessormechanism 103 in X-direction is maintained at X(i, j). Next, the accessoperation is carried out (step S224). After that, it is determinedwhether the access operation of step S224 has been normally completed(step S225). When it has been determined that the access operation ofstep S224 has been normally completed (Yes in step S225), αY/βY issubtracted from Y(i, j)(step S226), the obtained Y(i, j) is written intothe rewritable nonvolatile memory 303 (step S227), and the flow advancesto step S229 (FIG. 8).

When it has been determined that the access operation of step S224 hasnot been normally completed (No in step S225), the operation is endedafter abnormal termination processing (step S228).

Referring to FIG. 8, in step S229, the accessor mechanism 103 is shiftedto the position corresponding to the entrance of the tape drive 101 inX-direction. Next, the picker mechanism 104 is shifted to the positioncorresponding to the entrance of the tape drive 101 in Y-direction (stepS230). The loading operation is then carried out (step S231) and theoperation is ended.

The above value of αX at the taking-out time is set to a value more than0 and not more than the X-direction length ΔX (FIG. 10) of the normaltaking-out area 131. This can prevent the stop position in X-directionin step S207 from getting too long to get to the normal taking-out area131 in a case where the stop position in X-direction in step S202 hasbeen too short to get to the normal taking-out area 131 and can preventthe stop position in X-direction in step S212 from getting too short toget to the normal taking-out area 131 in a case where the stop positionin X-direction in step S202 has been too long to get to the normaltaking-out area 131. As shown in FIG. 12, as long as the value of αXfalls within the above range, the area obtained by adding areas 132 and133 to the normal taking-out area 131 can be set as the taking-outfeasible area. The X-direction length δX of the taking-out feasible areacan be obtained by adding (2×αx) to ΔX (δX=ΔX+2×αx).

Setting the value of αx at the length of ΔX can make the X-directionlength δX of the taking-out feasible area extend up to the maximum valueof 3×ΔX.

On the other hand, when the value of αx is set to the length of ΔX/2,the X-direction length δX of the taking-out feasible area is reduced to2×ΔX. However, in a case where misalignment gradually increases to causethe stop position in X-direction in step S202 to slightly deviate fromthe normal taking-out area 131, the stop position in X-direction in stepS207 or S212 can be set to the vicinity of the center of the normaltaking-out position 131.

The above value of βx is set as follows.

Firstly, in order to avoid occurrence of hunting and diverging phenomenaat the stop position in X-direction X(i, j) due to update of the stopposition in X-direction X(i, j), the values of αx and βx must be setsuch that αx/βx becomes not more than ΔX.

Further, it is assumed, for example, that the value of αx is set to thevalue of ΔX. In this case, when the value of βx is set to 2, αx/βxbecomes ΔX/2, with the result that the stop position in X-direction X(i,j) after compensation is set to the vicinity of the center of the normaltaking-out area 131 in a case where the stop position in X-direction instep S202 has slightly deviated from the normal taking-out area 131 andthe compensation takes place. Further, it is assumed, for example, thatthe value of αx is set to the value of ΔX/2. In this case, when thevalue of βx is set to 1, αx/βx becomes ΔX/2, with the result that thestop position in X-direction X(i, j) after compensation is set to thevicinity of the center of the normal taking-out area 131 in a case wherethe stop position in X-direction in step S202 has slightly deviated fromthe normal taking-out area 131 and the compensation takes place. If wesuppose that most of the causes of the failure of the accessingoperation in step S204 lie in that the stop position in X-direction instep S202 slightly deviates from the normal taking-out area 131, and, inthis case, in order to set the compensated stop position in X-directionX(i, j) to the vicinity of the center of the normal taking-out area 131,then the values of αx and βx should be set such that αx/βx becomes ΔX/2.

Further, there is a case where the stop position in X-direction in stepS202 has largely deviated from the normal taking-out area 131. In thiscase, in order to increase the possibility that the initial accessoperation (step S204) succeeds in the next operation starting from stepS201 after compensation, it is preferable that the value of αx/βx beclose to and not more than ΔX.

The setting of the values of the above αx and βx at the insertion timecan be explained by replacing the term “taking-out” with “insertion” inthe above seven paragraphs.

The setting of the values of the αY and βY at the taking-out andinsertion time can be explained by replacing the term “X” with “Y”,“step S202” with “step S203”, “step S207” with “step S218”, “step S212”with “step S223”, and “areas 132 and 133” with “areas 134 and 135” inthe above eight paragraphs.

In the above description, the rewritable nonvolatile memory 303 storesthe stop positions in X-direction X(i, j) and in Y-direction Y(i, j).Alternatively, however, the following method can be adopted. The methodincludes: storing a compensation amount of the stop position inX-direction and compensation amount of the stop position in Y-directionfor each cell in the rewritable nonvolatile memory 303; calculating astop position in X-direction and stop position in Y-direction beforecompensation based on X-origin and Y-origin of the magazine 102, theorder of a target cell in X-direction and that in Y-direction, and cellwidth and height; obtaining a stop position in X-direction X(i, j) byadding the compensation amount of the stop position in X-direction tothe stop position in X-direction before compensation; and obtaining astop position in Y-direction Y(i, j) by adding the compensation amountof the stop position in Y-direction to the stop position in Y-directionbefore compensation. In this case, the compensation amount of the stopposition in X-direction is updated in step S210 or S215, and thecompensation amount of the stop position in Y-direction is updated instep S221 or S226.

Further, in the above description, the accesses are attempted in fivepoints 401 to 405 arranged crosswise with the initial stop position(stop position in X-direction X(i, j), stop position in Y-direction Y(i,j)) as a center, as shown in FIG. 13A. Alternatively, however, theaccesses may be made in nine points 401 to 409 arranged in a latticemanner with the initial stop position (stop position in X-direction X(i,j), stop position in Y-direction Y(i, j)) as a center, as shown in FIG.13B. By this, it becomes more likely that the access succeeds in any ofthe additional four points 406 to 409 even in a case where the initialstop position (stop position in X-direction X(i, j), stop position inY-direction Y(i, j)) has deviated from the normal taking-out area ornormal insertion area both in X- and Y-directions.

Further, in the above description, the accesses are made in the fivepoints shown in FIG. 13A in the order of 401, 402, 403, 404, and 405.However, as long as the first access is made in the point 401, thesucceeding accesses can be made in any order.

In a case where the accesses are made in the nine points 401 to 409shown in FIG. 13B, as long as the first access is made in the point 401,the succeeding accesses can be made in any order.

Further, in the above description, the tape cartridge is taken as anexample of a cartridge. Besides, the present invention is applicable to,for example, a magnetic optical disk cartridge, a DVD cartridge, and thelike.

1. A system for accessing a cell, comprising an accessor means forremoving and inserting a tape cartridge from a target cell; a pickermechanism associated with the accessor means for taking possession ofand releasing a tape cartridge; a plurality of cells for storing tapecartridges, the cells being arrayed in a matrix; a memory for storingstop positions of the accessor means and the picker mechanismcorresponding to each cell including an initial stop position of theaccessor means and the picker mechanism, wherein the stop position ofthe accessor means is designated by an X coordinate and the stopposition of the picker mechanism is designated by an Y coordinate; adrive mechanism for driving the accessor means and the picker mechanismto the stop positions corresponding to each cell according to the Xcoordinate and the Y coordinate stored in the memory, and for drawingthe picker mechanism through the removal of a tape cartridge from a celland the insertion of a tape cartridge from a cell; a detection means fordetecting whether the accessor means has successfully removed orinserted the tape cartridge to or from the cell based on the alignmentbetween the accessor means or the picker mechanism and the correspondingcell; and a microcontroller means for compensating the misalignmentbetween the accessor means or the picker mechanism and the correspondingcell when the tape cartridge is not successfully removed or insertedrelative to the cell, by updating the stop positions by way ofincrementally adjusting at lease one of the X coordinate and the Ycoordinate, instructing the drive mechanism to drive the accessor meansand the picker mechanism at the updated stop positions to retry theremoval and insertion of the tape cartridge relative to the cell,wherein the microcontroller means rewrites the X coordinate and the Ycoordinate of the updated stop positions into the memory upon thesuccessful completion of the removal or insertion of the tape cartridgerelative to the cell.
 2. The system according to claim 1, furthercomprising access operation terminating means for terminating theremoving or inserting of a tape cartridge from a target cell where theaccessor means has failed to remove or insert the tape after apredetermined number of removal or insertion retries.
 3. The systemaccording to claim 1, wherein the updated stop positions include atleast four positions differentiated from the initial stop position inthe left, right, up and down directions, relative to the initial stopposition.
 4. The system according to claim 1, wherein the updated stoppositions includes eight positions differentiated from the initial stopposition arranged in a lattice manner at which four cross-shapesintersect with each other, the centers of the four cross-shapesextending from each of four positions apart from the initial stopposition in the left, right, up and down directions.
 5. The systemaccording to claim 1, wherein the incremented adjustment of at least oneof the X coordinates of the accessor means corresponds to one of theupdated stop positions differentiated from the initial stop position ina predetermined direction by a distance not more than the length of anormal removal area or normal insertion area.
 6. The system according toclaim 5, wherein the incremented adjustment of the X coordinate of theaccessor means corresponds to one of the updated stop positionsdifferentiated from the initial stop position in a predetermineddirection by a distance equal to the length of a normal removal area ornormal insertion area.
 7. The system according to claim 5, wherein theincremented adjustment of the X coordinate of the accessor meanscorresponds to one of the updated positions differentiated from theinitial stop position in a predetermined direction by a distance equalto the half of the length of a normal removal area or normal insertionarea.
 8. The system according to claim 1, wherein a difference betweenthe initial stop position and one of the updated stop positions in apredetermined direction is set to not more than the length of a normalremoval area or normal insertion area in the predetermined direction. 9.The system according to claim 8, wherein the difference between theinitial stop position and one of the updated stop positions in apredetermined direction is set equal to the length of a normal removalarea or normal insertion area in the predetermined direction.
 10. Thesystem according to claim 8, wherein the difference between the initialstop position and one of the updated stop positions in a predetermineddirection is set to half of the length of a normal removal area ornormal insertion area in the predetermined direction.
 11. A method foraccessing a cell adapted for retaining a tape cartridge comprising: (a)at least one first access step comprised of an attempt to complete oneof a taking out a cartridge from a cell or inserting the cartridge intothe cell, the first access step occurring at an initial stop positiondesignated by an X coordinate and a Y coordinate; (b) at least onedetermination step, to determine whether the first access step hassucceeded or failed; (c) if it is determined that the first access stephas failed, a step of obtaining updated stop positions relative to theinitial stop position by incrementally adjusting at least one of the Xcoordinate and the Y coordinate; (d) if it is determined that the firstaccess step has failed, at least one subsequent access step of takingout the cartridge from the cell or inserting the cartridge into thecell, at one of the updated stop positions; (e) if the at least onesubsequent access step was necessary, at least one subsequentdetermination step to determine whether the subsequent access step hassucceeded or failed; and (f) if it is determined that the subsequentaccess step has failed, a step of repeating (c)-(e).
 12. The methodaccording to claim 11, further comprising: a step of terminating thesubsequent access step in a case where the subsequent access step hasfailed to complete the taking-out or insertion operation in apredetermined number of the updated stop positions.
 13. The methodaccording to claim 11, wherein the updated stop positions include fourpositions apart from the initial stop position in the left, right, upand down directions.
 14. The method according to claim 11, wherein theupdated stop positions include eight positions obtained by excluding theinitial stop position from nine positions arranged in a lattice mannerat which four cross-shapes intersect with each other, the centers of thefour cross-shapes extending from each of four positions apart from theinitial stop position in the left, right, up and down directions. 15.The method according to claim 11, wherein at least one of the updatedstop positions is set at the position apart from the initial stopposition in a particular direction by a distance not more than thelength of a normal taking-out area or normal insertion area.
 16. Themethod according to claim 15, wherein at least one of the updated stoppositions is set at the position apart from the initial stop position ina particular direction by a distance equal to the length of a normaltaking-out area or normal insertion area.
 17. The method according toclaim 15, wherein at least one of the updated stop positions is set atthe position apart from the initial stop position in a particulardirection by a distance equal to the half of the length of a normaltaking-out area or normal insertion area.
 18. The method according toclaim 11, further comprising: an step of rewriting the X coordinate andY coordinate of the updated stop position to a memory if it isdetermined that the subsequent access step succeeded.
 19. The methodaccording to claim 18, wherein a difference between the initial stopposition and one of the updated stop positions in a particular directionis set to not more than the length of a normal taking-out area or normalinsertion area in the particular direction.
 20. The method according toclaim 19, wherein a difference between the initial stop position and oneof the updated stop positions in a particular direction is set to equalto the length of a normal taking-out area or normal insertion area inthe particular direction.
 21. The method according to claim 19, whereina difference between the initial stop position and one of the updatedstop positions in a particular direction is set to the half of thelength of a normal taking-out area or normal insertion area in theparticular direction.